Sun L. C.; Meinhold, C. B.Health Physics: July 1997 Papers: PDF Only Buy Abstract The gastrointestinal absorption constant (f1) is a critical parameter in assessing systemic uptake following the ingestion of a radioactive material and in monitoring such intakes. This study addresses the latter, particularly for plutonium, and from environmental measurements derives an f1 value of 4 × 10−4 for the Marshallese population. The uncertainty associated with the methodology and measurements used in this f1 value assessment is evaluated. This evaluation takes into account the results from 24-h urine samples and the particular lifestyle of the Marshallese. Plutonium intake resulting frem soil consumption is a primary parameter in this evaluation; for this study, it was assumed to be 500 mg d−1. The f1 value determined here is consistent with the values in ICRP Publication 67 of 5x10−4 for ages 1 to adult, and is the same as that suggested by the NRPB. © Lippincott-Raven Publishers.